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Article
Year: 2000
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A number of studies have demonstrated that both morphological and biochemical indices in the brain undergo alterations in response to environmental influences. In previous work we have shown that rats raised in an enriched environmental condition (EC) perform better on a spatial memory task than rats raised in isolated conditions (IC), We have also found that EC rats have a higher density of immunoreactivity than IC rats for both low and high affinity nerve growth factor (NGF) receptors in the basal forebrain. In order to determine if these alterations were coupled with altered levels of neurotrophins in other brain regions as well, we measured neurotrophin levels in rats that were raised in EC or IC conditions. Rats were placed in the different environments at 2 months of age and 12 months later brain regions were dissected and analyzed for NGF, brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) levels using Promega ELISA kits. We found that NGF and BDNF levels were increased in the cerebral cortex, hippocampal formation, basal forebrain, and hindbrain in EC animals compared to age-matched IC animals. NT-3 was found to be increased in the basal forebrain and cerebral cortex of EC animals as well. These findings demonstrate significant alterations in NGF, BDNF, and NT-3 protein levels in several brain regions as a result of an enriched versus an isolated environment and thus provide a possible biochemical basis for behavioral and morphological alterations that have been found to occur with a shifting environmental stimulus. (C) 2000 Academic Press
Affinity ngf receptors. --- Age. --- Aged rats. --- Alzheimers-disease. --- Animal. --- Animals. --- Biochemical. --- Brain. --- Cerebral-cortex. --- Cholinergic neuron atrophy. --- Cognitive dysfunction. --- Cortex. --- Density. --- Elisa. --- Enriched. --- Enrichment. --- Environment. --- Environmental enrichment. --- Environments. --- Factor messenger-rna. --- Growth. --- Hippocampal slices. --- Hippocampal-formation. --- Hippocampal. --- Immunoreactivity. --- Increase. --- Increases. --- Learning deficits. --- Level. --- Long-term. --- Memory. --- Nerve growth-factor. --- Neurotrophic factor. --- Neurotrophin,ngf,bdnf,nt-3,elisa,enriched environment. --- Ngf. --- Protein. --- Rat-brain. --- Rat. --- Rats. --- Receptor. --- Receptors. --- Response. --- Spatial memory. --- Spatial. --- Stimulus. --- Task. --- Visual-cortex. --- Work.
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The degree to which memory is enhanced by estrogen replacement in postmenopausal women may depend on environmental factors such as education. The present study utilized an animal model of environmental enrichment to determine whether environmental factors influence the mnemonic and neural response to estrogen. Female mice were raised in standard (SC) or enriched (EC) conditions from weaning until adulthood (7 months). All mice were ovariectornized at 10 weeks, and tested in object recognition and water-escape motivated radial arm maze (WRAM) tasks at 6 months. Each day at the completion of training, mice received injections of 0.1 mg/kg cyclodextrin-encapsulated 17-beta-estradiol (E-2), 0.2 mg/kg E-2, or cyclodextrin vehicle (VEH). At the completion of behavioral testing, hippocampal levels of the presynaptic protein synaptophysin and of brain-derived neurotrophic factor (BDNF) were measured. Enrichment effects were evident in VEH-treated mice; relative to SC-VEH females, EC-VEH females committed fewer working memory errors in the WRAM and exhibited increased hippocampal synaptophysin levels. Estrogen effects depended on environmental conditions. E-2 (0.2 mg/kg) improved object memory only in SC females. The same dose improved working memory in SC females, but somewhat impaired working memory in EC females. Furthermore, both doses reduced hippocampal synaptophysin levels in EC, but not SC, females. In contrast, E-2 reduced hippocampal BDNF levels in SC, but not EC, females. This study is the first to compare the effects of estrogen on memory and hippocampal function in enriched and non-enriched female mice. The results suggest that: (1) estrogen benefits object and working memory more in mice raised in non-enriched environments than in those raised in enriched environments, and (2) the changes induced by estrogen and/or enrichment may be associated with alterations in hippocampal synaptic plasticity. (C) 2004 Published by Elsevier Ltd on behalf of IBRO
Adulthood. --- Aged female mice. --- Animal model. --- Animal-model. --- Animal. --- Bdnf. --- Dendritic spine density. --- Education. --- Enriched environment. --- Enriched. --- Enrichment. --- Environment. --- Environmental enrichment. --- Environments. --- Estradiol. --- Estrogen. --- Factor messenger-rna. --- Female mice. --- Female. --- Females. --- Function. --- Health initiative memory. --- Hippocampal. --- Hippocampus. --- Hormone replacement therapy. --- Injections. --- Level. --- Memory consolidation. --- Memory. --- Mice. --- Model. --- Neurotrophic factor. --- Object recognition. --- Object. --- Plasticity. --- Postmenopausal women. --- Protein. --- Radial arm maze. --- Radial-arm maze. --- Randomized controlled-trial. --- Recognition. --- Replacement. --- Response. --- Spatial reference memory. --- Synaptic plasticity. --- Synaptophysin. --- Task. --- Tasks. --- Time. --- Training. --- Weaning. --- Women. --- Working memory. --- Working-memory.
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